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Higher occurrence of Parkinson's linked to low LDL
cholesterol

Newswise — People with low levels of LDL cholesterol
are more likely to have Parkinson's disease than
people with high LDL levels, according to University
of North Carolina at Chapel Hill researchers.

LDL stands for low-density lipoprotein cholesterol;
low levels of LDL cholesterol are considered an
indicator of good cardiovascular health. Earlier
studies have found intriguing correlations between
Parkinson's disease, heart attacks, stroke and
smoking.

"People with Parkinson's disease have a lower
occurrence of heart attack and stroke than people
who do not have the disease," said Dr. Xuemei Huang,
medical director of the Movement Disorder Clinic at
UNC Hospitals and an assistant professor of
neurology in the UNC School of Medicine.
"Parkinson's patients are also more likely to carry
the gene APOE-2, which is linked with lower LDL
cholesterol." And for more than a decade,
researchers have known that smoking, which increases
a person's risk for cardiovascular disease, is also
associated with a decreased risk of Parkinson's
disease.

These findings led Huang to examine whether higher
LDL cholesterol might be associated with a decreased
occurrence for Parkinson's disease, and vice versa.
"If my hypothesis was correct," she said, "lower LDL-C,
something that is linked to healthy hearts, would be
associated with a higher occurrence of Parkinson's."

The results of Huang's study, published online Dec.
18 by the journal Movement Disorders,
confirmed her hypothesis. "We found that lower LDL
concentrations were indeed associated with a higher
occurrence of Parkinson's disease," Huang said.
Participants with lower LDL levels (less than 114
milligrams per deciliter) had a 3.5-fold higher
occurrence of Parkinson's than the participants with
higher LDL levels (more than 138 milligrams per
deciliter).

Huang cautioned that people should not change their
eating habits, nor their use of statins and other
cholesterol-lowering drugs, because of the results.
The study was based on relatively small numbers of
cases and controls, and the results are too
preliminary, she said. Further large prospective
studies are needed, Huang added.

"Parkinson's is a disease full of paradoxes," Huang
said. "We've known for years that smoking reduces
the risk of developing Parkinson's. More than 40
studies have documented that fact. But we don't
advise people to smoke because of the other more
serious health risks," she said.

Research funding was provided by the National
Institute on Aging, the Intramural Research Program
of the National Institute of Environmental Health
Sciences and the General Clinical Research Center at
UNC Hospitals.

Huang and her colleagues recruited 124 Parkinson's
patients who were treated at the UNC Movement
Disorder Clinic between July 2002 and November 2004
to take part in the study. Another 112 people, all
spouses of patients treated in the clinic, were
recruited as the control group.

Fasting cholesterol profiles were obtained from each
participant. The researchers also recorded
information on each participant's gender, age,
smoking habits and use of cholesterol-lowering
drugs.

Huang notes that the study also found participants
with Parkinson's were much less likely to take
cholesterol-lowering drugs than participants in the
control group. This, combined with the findings
about LDL cholesterol, suggests two questions for
additional study, Huang said.

"One is whether lower cholesterol predates the onset
of Parkinson's. Number two, what is the role of
statins in that? In other words, does taking
cholesterol-lowering drugs somehow protect against
Parkinson's? We need to address these questions,"
she said.

Huang's co-authors include Dr. Richard B. Mailman,
Jennifer L. Woodard, Peter C. Chen, and Drs. Dong
Xiang, Richard W. Murrow and Yi-Zhe Wang, all of the
UNC School of Medicine. Additional co-authors
include Dr. Honglei Chen of the National Institute
of Environmental Health Sciences and Drs. William C.
Miller and Charles Poole, both from the department
of epidemiology in the UNC School of Public Health.